This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Hormones are Chemically Diverse – Set 2”.
1. Name a hormone which is produced from vitamin D?
a) Testosterone
b) Progesterone
c) Parathormone
d) Calcitriol
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Explanation: Hydroxylation reactions in the liver and kidneys produces calcitriol (1,25-dihydroxycholecalciferol) from vitamin D. Vitamin D can be obtained in two ways; either from the diet or by the photolysis of 7-dehydrocholesterol in the skin which is exposed to sunlight.
2. Which enzyme is involved in the synthesis of corticosteroid hormones?
a) P-450 enzymes
b) Protein kinases
c) Lipases
d) Glycogen Phosphorylases
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Explanation: In the adrenal cortex, more than 50 corticosteroid hormones are released, by reactions which remove the side chain from the cholesterol D ring, and this introduces oxygen to form keto and hydroxyl groups. Many of these reactions contain enzymes of cytochrome P-450.
3. Which are the two general classes of steroid hormones present in the cell?
a) Aldosterone and testosterone
b) Glucocorticoids and mineralocorticoids
c) Peptide hormone and amine hormones
d) Thyroid hormones and sex hormones
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Explanation: There are two common forms of steroid hormones. They are Mineralocorticoids and Glucocorticoids. Glucocorticoids (such as cortisol) mainly influence carbohydrate metabolism; mineralocorticoids (such as aldosterone) regulate the electrolyte amounts in the blood.
4. Which are the hormones involved in maintaining calcium levels in the body?
a) Thyroid hormones
b) Sex hormones
c) Calcitriol and Parathormone
d) Epinephrine and norepinephrine
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Explanation: In calcium homeostasis, calcitriol functions in combination with parathyroid hormone. This controls calcium in the blood and maintain the equilibrium of calcium deposition. It also helps in the bone mobilization of calcium. Calcitriol that works by nuclear receptors, stimulates the synthesis of an intestinal protein that is necessary for dietary calcium absorption.
5. What is the name of the disease caused by the disorder in the metabolism of calcitriol?
a) Hypothyroidism
b) Goiter
c) Osteoporosis
d) Rickets
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Explanation: Inadequate dietary vitamin D or biosynthesis defects of calcitriol lead to extreme diseases like rickets. In this disease, the bones are damaged and malformed. The deficiency of vitamin D results in decreased calcium and phosphorus absorption. This is the primary cause of rickets.
6. Which class of hormones regulate the growth, survival, and differentiation of cells?
a) Retinoids
b) Steroids
c) Vitamin D hormones
d) Peptide hormones
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Explanation: Retinoids are potent hormones that control the growth, survival and differentiation of cells through nuclear retinoid receptors. The prohormone retinol is synthesized from beta-carotene, particularly in the liver, and retinol is converted to the hormone retinoic acid (RA).
7. Which among the following is the most important nuclear retinoid receptors in adults?
a) Muscles
b) Skin
c) Kidneys
d) Liver
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Explanation: All tissues are retinoid targets, since there is at least one kind of nuclear retinoid receptor in all cell types. In adults, the most critical targets include the skin, cornea, lungs and trachea, and the immune system. Among them, skin is the most important nuclear retinoid target.
8. What are the consequences of excessive vitamin A in women?
a) Acne
b) Tumor
c) Birth defects
d) Osteoporosis
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Explanation: Excessive vitamin A may cause birth defects and it is recommended that pregnant women should not use retinoid creams produced for the treatment of extreme acne. Excess vitamin A and retinoid consumption by pregnant women frequently results in malformations of the skulls, ears, arms, eyes and central nervous system of fetuses.
9. What is the precursor protein for the synthesis of thyroid hormones?
a) Albumin
b) Globulin
c) Fibrinogen
d) Thyroglobulin
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Explanation: T4 (thyroxine) and T3 (triiodothyronine) thyroid hormones are synthesized from the precursor protein thyroglobulin. In the thyroid gland, up to 20 Tyrosine residues in thyroglobulin are enzymatically iodinated. Then the two iodotyrosine residues condense to form the thyroxine precursor.
10. What are the three hormones produced by thyroid gland?
a) Triiodothyronine, Thyroxine and Calcitonin
b) Thyroxine, Calcitonin and epinephrine
c) Triiodothyronine, calcitonin and epinephrine
d) Epinephrine, norepinephrine and Calcitonin
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Explanation: Three hormones are produced by the thyroid gland namely; Triiodothyronine, also known as T3, Tetraiodothyronine, also known as thyroxine, or T4 Calcitonin. Only T3 and T4 are proper thyroid hormones on practical scenario. They are formed in the thyroid’s follicular epithelial cells.
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
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